one fired in self-defense. police chief kathy lanier hugged one of her officers on the scene. investigators pick up a hoels ere and place t in the trunk of an unmarked call. it was a close call responding to a 911 dispatch. a d.c. police officer became the victim when he was attacked by a man with a knife. >> officers received the call about 6:45 for domestic assault. when they arrived on the scene and approaching the house, apparently the suspect came up from behind the officers and attacked. one of the officers has several stab wounds to his head, neck and hands. the officer then turned around and gave the suspect and shots were fired. >> reporter: is suspect died on the scene. also injured, the grandfather of the dead suspect. he was attacked by his grandson early in the morning prompting the 911 call and response. what follows next serves as a reminder of how dangerous and unpredictable police work can be. >> this is traumatic for officers. the last thing we want to do is take a life. it's upsetting for the officers here. >> reporter: the chief says the injured officer has